In previous centuries, leeches were widely used to cleanse human blood. However, in the last century there was a peak in popularity for these worms, as a result of which their collection and intensive destruction of the natural habitat of leeches led to a reduction in their numbers. Today, worms are propagated for medical purposes in specialized laboratories.
Characteristics
The leech's body has a ringed appearance, but is slightly flattened than that of worms. And the stomach is a modified midgut. Most species of these worms have eyes, but all circulatory system closed type.
Each individual has two suckers:
- back;
- front
With the help of these suckers, the worm attaches itself to the victim, as well as to surrounding objects. With their help, the leech moves.
Diet
What do leeches eat in nature? In most cases, leeches feed on the blood of mollusks, vertebrates and other representatives of the animal world. It is these types (not all) that are used for medical purposes.
Medical leeches have three jaw plates on which great amount small and very sharp teeth. The jaws themselves are a collection of thick muscles. At first, the leech pierces with its teeth skin covering, then tears the tissue and sucks out the blood. After a bite from sebaceous glands The worm's sucker secretes a protein substance called hirudin. It prevents blood from clotting, but on the contrary, provokes its flow to the wound. In addition, saliva with anesthetic properties is secreted, so the worm for a long time manages to remain unnoticed.
One of the representatives of this subspecies is the fish leech, which swims beautifully, unlike medical leech. What do leeches of this species eat? Tissue fluid of fish.
These are quite large worms and can reach 50 centimeters in length. They do not disdain almost any type of fish; more than 100 worms can be found on one.
When the leech is not eating, it calmly swims in a pond or “sits” on aquatic plants. It does not pose any danger to humans. In winter, these worms do not hibernate, and without fish they can live up to 3 months.
Habitat - Eurasia, lakes and large rivers, very rare, but found in wastewater. Prefers fish from the genus carp.
By the way, this worm can appear in an aquarium. What do leeches eat in such cases? All the same tissue fluid. It is quite difficult to deal with such a problem in a closed reservoir; most likely, complete disinfection and disinfection will be required. They can get into the aquarium along with live food.
The snail leech also belongs to the proboscis annelids. This is a very slow creature that does not even move independently, but completely relies on the current. What do leeches eat? Mainly with the blood of pulmonary freshwater mollusks, and these are, first of all, pond snails. After a worm attack, as a rule, the snail dies, since the leech causes a blockage respiratory tract. Worms are also brought into the aquarium with live food.
The closest relatives of these species include bird leeches - species that “feast” on the blood of Kamchatka crab and shrimp.
These worms are also called Nile or Egyptian worms. They live in Central Asia and in the Mediterranean, Transcaucasia. They prefer small fresh water bodies.
What do leeches eat in a pond? The horse species also prefers blood, but does not have a developed jaw, so it attaches itself to the mucous membranes of the victim when it bathes in a pond. Most often, horses become victims, but the worm does not disdain other artiodactyls, amphibians, and even representatives of the human race. They can even attach to the conjunctiva of the eye. The most dangerous thing about these worms is that once they enter the body, they greatly increase in size and if they enter through the mouth, they can cause blockage of the respiratory tract and, as a result, suffocation.
Predatory leeches
The most common species in Asia and Europe is the small false horse leech. What do leeches eat in bodies of standing water? Oddly enough, they consume invertebrate representatives of the animal world. These are insect larvae - microscopic worms. The small false horse leech itself reaches a maximum length of 6 centimeters, and can itself become a victim of fish or an invertebrate predator.
The Erpobdella leech acts in a similar way. It is quite large and can be seen from afar. This is an excellent swimmer, but the worm does not have a proboscis, but its body is equipped with a powerful mouth. What do leeches eat? All the same invertebrates, these are mollusks, fish fry, crustaceans, insect larvae. This worm does not even disdain carrion.
After a medicinal leech bite, the bleeding may not stop for a whole day. The largest leech is 30 centimeters long.
First time growing annelids for medical purposes they began in Wales, from where leeches are still supplied today. But the most interesting thing is that there are leeches that, in addition to invertebrate fauna, consume vegetation.
The long-awaited report from the leech farm. You will learn how leeches live in captivity, what they eat, and how they reproduce. For the first time, we were able to capture unique footage of the birth of a leech in natural conditions and in captivity.
Five pairs of eyes intensely watched the water column, all senses aimed at finding the victim. For more than three weeks now, in search of food, they have had to move from one corner of the reservoir to another. Even repeated forays onto land did not bring the desired result. Sad thoughts overwhelmed the vampire. Blood and only blood... “Okay, you can hold out for another three months, but if luck doesn’t smile, you’ll have to emigrate to a nearby body of water; they say that cattle come there to drink...” There was a splash somewhere, another, a third - the steel muscles tensed. The vampire identified the source of the vibrations and, with smooth wave-like movements, directed his body towards the victim. Here she is! Light, warm body, and so little fur, just not to miss. The vampire straightened his huge mouth, exposed three terrible jaws with sharp teeth and bit into the victim... A heartbreaking cry filled the water surface of the reservoir.
01.
02. Today we will tell you about International Center medical leech, created on the basis of the Medpiyavka association formed in 1937, which was engaged in keeping leeches in artificial ponds in the dacha village of Udelnaya (Moscow region). 
03. At 2500 sq. m. are located industrial premises for growing more than 3,500,000 medicinal leeches and producing cosmetic products. 
04. In total, science knows 400 species of leeches, which look approximately the same and differ mainly in color. Leeches are black, greenish or brownish. Russian name These nimble worms indicate their ability to “bite” into the victim’s body and suck out blood. 
05. Leeches live in three-liter jars. They couldn’t come up with anything better as a house for them. The leechkeeper must ensure that the vessel with leeches is constantly covered with a thick white cloth, which is tied tightly. 
06. Leeches are unusually mobile and often tend to crawl out of the water. Therefore, they are able to easily leave the container in which they are stored. Escapes occur periodically. 
07. A leech has 10 eyes, but the leech does not perceive a complete image. Despite the seeming primitiveness of the sensory perception of leeches, they are excellent at orienting themselves in space. Their sense of smell, taste and touch are unusually developed, which contributes to their success in finding prey. First of all, leeches respond well to odors emanating from objects immersed in water. Leeches cannot tolerate foul-smelling water. 
08. Slow, devoid of sharpness movements allow you to see the entire body of the leech. On the back, against a dark background, bright orange inclusions form a bizarre pattern in the form of two stripes. On the sides there is black edging. The abdomen is delicate, light olive in color with a black edging. The body of an ordinary medicinal leech consists of 102 rings. On the dorsal side the rings are covered with many small papillae. On the ventral side there are much fewer papillae and they are less noticeable. 
09. But behind the harmless external beauty The leech hides its secret weapon - the front sucker, outwardly invisible. The large, intimidating rear sucker does not cause any physical damage, but in the depths of the front jaws are hidden, geometrically located according to the sign of the prestigious company of the automotive world - Mercedes. There are up to 90 teeth in each jaw, for a total of 270. This is deceit. 
10. The record for the maximum size of a leech grown in this center is 35 centimeters in length. The leech in the photo still has everything ahead. 
11. A leech bit me like a nettle stung. The bite of the same horsefly or ant is much more painful. Leech saliva contains painkillers (analgesics). The leech feeds exclusively on blood. Hematophage, that is, a vampire. 
12. The epidermal layer of the leech is covered with a special film - cuticle. The cuticle is transparent, it performs protective function and grows continuously, periodically being renewed during the molting process. Normally, leeches moult every 2-3 days. 
13. Discarded films resemble white flakes or small white covers. They clog the bottom of the vessels for storing used leeches, and therefore must be removed regularly, and the water is also periodically colored from digestion products. The water is changed twice a week. 
14. The water is specially prepared: it sits for at least a day, it is purified from harmful impurities And heavy metals. After cleaning and passing control, the water is heated to the required temperature and enters the common network for leeches. 
15.
16. Leeches poop up to several times a day, so the water in the vessel where used leeches are stored periodically becomes colored. Clogging of water that occurs from time to time does not cause any harm to leeches if the water is regularly changed. 
17. The most important condition A way to quickly grow full-fledged medicinal leeches is to regularly feed them with fresh blood, which is purchased from slaughterhouses. 
18. Large clots formed during coagulation of blood mass are used. To fully feed leeches, only the blood of healthy animals, mainly large and small, is taken. cattle. The clots are placed at the bottom of special vessels, into which the leeches are then released. 
19. To make it pleasant for leeches to eat, a film is laid on them, which they, out of habit, bite through and suck blood. 
20. During growth, the leech feeds every one and a half to two months. 
21. After the leeches have grown and fasted for at least three months, they are collected in series and sent for certification, and then they go on sale or are used in the production of cosmetics. The Center has an accredited laboratory of the quality control department. But more about this tomorrow. 
22. During one feeding, a leech sucks out five times its own weight, after which it may not eat for three to four months, or a maximum of a year. After eating, the leech looks like a solid muscle sac filled with blood. In her digestive tract There are special substances that protect blood from putrefaction, which preserve it in such a way that the blood always remains complete and is stored for a long time. 
23. A leech usually eats its fill in 15-20 minutes. A sign that the leech is full is the appearance of foam. 
24. Well-fed leeches are trying to escape from the “dining room”. 
25. Yum-yum! 
26. After feeding, the leeches are washed. 
27. And put it back in the jar. 
28. 
29. And the dishes are washed. 
30. 
31. Leeches communicate with each other extremely rarely, only during the mating period. And then, most likely, out of necessity, so as not to die out. Suitable for reproduction, that is, thoroughly fed and reached given dimensions leeches are called queens. 
32. They are placed in pairs in jars filled with water and stored in special rooms where the optimal environmental temperature is maintained to maintain the activity of leeches and their reproductive abilities. Copulation and laying of cocoons with eggs occur in leeches at an environmental temperature of 25 to 27 °C. And although each individual carries within itself both the male and female principles (hermaphrodites), it cannot satisfy itself in this intimate matter and is looking for a partner. 
33. The mating season, during which mating occurs, takes about 1 month, after which the leeches are seated in queen cells - three-liter jars. Moist peat soil is placed at the bottom of the queen cell, providing a favorable environment for medicinal leeches and their cocoons. On top of the peat are soft moss turfs that regulate soil moisture. The queens move freely on the moss, in which they feel comfortable, and gradually burrow into the peat. 
34. Leeches practice different positions in which copulation occurs. There are 2 main positions having biological meaning. First position: the anterior ends of the bodies of copulating leeches are directed in one direction. The second main position: the ends of the bodies are oppositely directed, that is, they look in different directions. 
35. The peat is thoroughly washed so that the leeches are moist and comfortable. 
36. 
37. You can identify a pregnant leech by the light rings and place it in a jar of peat. 
38. Breaking a shallow hole in the soil, the leech lays a cocoon in it, from which filaments are subsequently hatched - this is what the leech breeders of small young leeches are called. Their mass reaches 0.03 g at most, and their body length is 7-8 mm. The filaments are fed in the same way as adults. 
39. Each mother leech lays an average of 3-5 cocoons, each of which contains 10-15 fry. 
40. After a while, the cocoons become like soft foam balls. 
41. In the light you can see that the fry are sitting inside the cocoon. 
42. And here are unique shots of the birth. The leech leaves the cocoon through a hole in the end. 
43. 
44. The first minutes of life of a small leech. 
45. And this is how they are born in the conditions of the center. The cocoons are simply torn apart. 
47. As shown laboratory research, the average lifespan of a leech is 6 years. Scientists do not know for certain how long wild individuals live, although it is possible that leeches have their own long-livers. 
Tomorrow at this time there will be a story about how leeches are killed to help people. What happens to a leech after it has sucked blood from a person? How are these cute worms tortured? How to make leech powder and much more!
Text:
Book by D.G. Zharov "Secrets of Hirudotherapy"
Book "Vampire's Kiss". Authors: Nikonov G.I. and Titova E.A.
Previously, the medicinal leech lived in almost every corner of Europe, but now its numbers have sharply decreased. This happened because active commercial fishing in the past, as well as drainage of swamps, significantly reduced the population.
The body of the medicinal leech is flattened, rounded, with two suckers that grow at the front and rear ends. The anterior sucker is crowned with a mouth opening.
In its natural habitat, the leech attaches itself to various underwater plants, where it waits for prey. The leech is very voracious; with a weight of about 2 g, it can easily suck up to 15 ml of blood in one go, while its body weight increases almost 10 times.
The blood that the leech has sucked from the victim does not clot and can remain in a liquid state for up to several months. The period that she can live from the first meal to the next is about 2 years.
To digest blood and keep it in its original liquid form, special bacteria called Aeromonas hydrophila are found in the leech’s intestines. Leeches have a symbiotic relationship with these microorganisms. This means that both participants in the tandem benefit. In addition, if there are unwanted bacteria in the leech’s stomach, the symbiont destroys them, purifying the blood contained in the worm.
The use of leeches in domestic medicine is aimed against diseases such as varicose veins, bleeding (hemorrhage), and ulcers. In the West and in Europe, with the help of these worms they fight venous stagnation, which is formed during tissue transplantation. Some medicines contain leech extract. Today, technological progress allows attempts to create an artificial leech.
Distribution area of medicinal leeches
Live in large quantities in the north to the border with Scandinavia, in the south – to Algeria and Transcaucasia. There is an assumption that within the boundaries of their habitat, they live in isolated populations, avoiding contact with groups of other leeches. The form of leeches used in medicine lives mainly in Azerbaijan and Transcaucasia. Another form, pharmaceutical, lives in Krasnodar region, Stavropol region.
Typical habitat of leeches
Leeches are adapted to aquatic and air habitats. To pump from one body of water to another, they are able to travel long distances overland. They live only in fresh waters. They do not tolerate salty water sources. The usual place where they live is lakes or ponds, the bottom of which is lined with silt. Prefer clean water, where frogs live and reeds grow thickly.
The International Union for Conservation of Nature (IUCN) classifies medicinal leeches as numerically vulnerable animals. Some habitats that have long been familiar to leeches are no longer areas of their distribution. The reason for the decline in numbers is the massive outflow for medical purposes. Today, the intensity of population depletion has decreased due to the fact that the bloodletting technique has become irrelevant.
Also, biofactories are being created in which leeches are artificially grown, however, this does little to restore the population. Also an obvious factor that leads to death large number of these animals is the reduction in the number of frogs. They are the main source of nutrition for small leeches that are not able to penetrate to larger animals.
Features of the body structure of leeches
As mentioned earlier, the medicinal leech has an elastic body, elongated, with well-developed muscles. It is divided into 33 segments. It has two suckers, the back one is larger than the front one, its function is to attach itself to the substrate. Each segment is divided into a certain number of segments (3 or 5); sensory papillae are located in the central ring of each segment.
The abdomen and back differ in color, the back is dark, with brown stripes. The outside of the body has a cuticle; it is shed repeatedly during growth. By the intensity with which the animal sheds, you can determine the health status of the leech.
The leech has four layers of muscles. The first consists of circular fibers, responsible for swallowing blood, followed by a layer of diagonal and deep longitudinal fibers, they provide contraction of the body, the last layer is the dorso-abdominal muscles, they serve to make the body flat. Connective tissue very elastic, dense, it covers both muscle fibers, and organs.
The nervous system consists of ganglia and segmental nerves extending from them. At the anterior and posterior ends of the body, the ganglia unite and form a pair of synganglia, one pharyngeal and one anal.
The receptors that are located on each segment are divided according to the type of sensitivity into three types: baroreceptors, thermoreceptors and chemoreceptors. All of them serve to search for food and navigate in space. On top of that, the first five segments contain five pairs of eyes, which include special pigment cells, with the help of them the leech can distinguish light from darkness.
The digestive system includes: the mouth, in the central part of the front sucker, jaws - one upper and two lower, each with 100 chitin teeth, they can damage the skin of the organism to which it is sucked. A special secretion also enters the mouth opening, which prevents the blood from clotting at the moment of absorption. The stomach is presented in the form of an elastic tube, which has 11 paired pockets. The muscular sphincter separates the stomach from the intestines. In the latter it accumulates feces, when removed, the water turns colored dark color.
Urine, which is formed in the leech’s body, is released through the nephropores. According to the type of reproduction, she is a hermaphrodite; she cannot fertilize herself alone; she still needs a pair.
Feeding and reproduction of leeches
It feeds mainly on the blood of warm-blooded animals, but can sometimes attack frogs and fish. The duration of blood absorption always varies depending on the state of the leech.
A hungry individual can take blood for 2 hours.
It breeds once a year, in summer. The copulation process occurs on land, the leeches wrap around each other and stick together, after fertilization the leech lays 5 cocoons, from which babies will be born after 2 weeks.
If you find an error, please highlight a piece of text and click Ctrl+Enter.
Names: medical leech, common leech.
Area: Central and Southern Europe, Asia Minor.
Description: medical leech - ringworm class of leeches. Breathing is cutaneous, there are no gills. The muscles are well developed (accounting for about 65% of the body volume). The outer covering is called the skin, which consists of a single layer of signet-like cells that form the epidermis. On the outside, the epidermal layer is covered with cuticle. The cuticle is transparent, performs a protective function and continuously grows, periodically being renewed during the molting process. Shedding occurs every 2-3 days. The shed skin resembles white flakes or small white covers. The body of the leech is elongated, but not whip-shaped, and consists of 102 rings. On the dorsal side the rings are covered with many small papillae. On the ventral side there are much fewer papillae and they are less noticeable. The head end is narrowed compared to the rear end. There are special suction cups on both ends of the body. The anterior sucker surrounding the mouth opening is the sucking circle. He triangular shape with three strong jaws, each of which has up to 60-90 chitinous teeth arranged in the form of a semicircular saw. Near the rear sucker there is an anus (powder). On the leech’s head there are ten small eyes arranged in a semicircle: six in front and four on the back of the head. With their help, a medicinal leech cuts through the skin to a depth of one and a half millimeters. Ducts open at the edges of the jaws salivary glands. Saliva contains hirudin, which prevents blood clotting. There are no kidneys. Two genital openings are located on the ventral side of the body, closer to the head end.
Color: Medical leech comes in black, dark gray, dark green, green, and red-brown colors. There are stripes on the back - red, light brown, yellow or black. The sides are green with a yellow or olive tint. The abdomen is motley: yellow or dark green with black spots.
Size: length 3-13 cm, body width up to 1 cm.
Lifespan: up to 20 years.
Habitat: fresh water bodies (ponds, lakes, quiet rivers) and damp places near water (clay, damp moss). Leeches love clean, running water.
Enemies: fish, muskrat.
Food/food: the medical leech feeds on the blood of mammals (humans and animals) and amphibians (including frogs), however, in the absence of animals, it eats the mucus of aquatic plants, ciliates, mollusks, and insect larvae living in water. It gently bites the skin and sucks out a small amount blood (up to 10-15 ml). It can live more than a year without food.
Behavior: if the reservoir dries up, the leech buries itself in the moist soil, where it waits out the drought. In winter it hibernates, hiding in the soil until spring. Does not withstand ground freezing. The characteristic pose of a hungry leech is that, having attached itself to a stone or plant with its rear sucker, it stretches its body forward and makes circular movements with its free end. Reacts quickly to many stimuli: splash, temperature and smell. When swimming, the leech greatly elongates and flattens, acquiring a ribbon-like shape and bending in a wave-like manner. The rear sucker in this case acts as a fin.
Reproduction: hermaphrodite. After fertilization, the leech crawls ashore, digs a small depression in the moist soil, in which it produces a foamy mass from the secretions of the oral glands. 10-30 eggs are laid in this depression, after which it returns to the water.
Breeding season/period: June August.
Puberty: 2-3 years.
Incubation: 2 months.
Offspring: Newborn leeches are transparent and similar to adults. They spend some time inside their cocoons, feeding on nutrient fluid. Later they crawl into the water. Before reaching sexual maturity, young leeches feed on the blood of tadpoles, small fish, earthworms or snails. If after three years a leech has never drunk the blood of mammals, then it will never reach sexual maturity.
Benefit/harm for humans: first information about the use of leeches with medical purposes belong to Ancient Egypt. Medical leech is used for bloodletting with medicinal purposes. IN modern medicine leeches are used to treat thrombophlebitis, hypertension, pre-stroke conditions, etc. Leech saliva entering the human body has healing properties unique properties- contains more than 60 biologically active substances.
Literature:1. Big Soviet encyclopedia
2. Vladislav Sosnovsky. Magazine "In the Animal World" 4/2000
3. Jan Zhabinsky. "From the Life of Animals"
4. D.G.Zharov. "Secrets of hirudotherapy"
Compiled by: , copyright holder: Zooclub portal
When reprinting this article, an active link to the source is MANDATORY, otherwise, use of the article will be considered a violation of the Law on Copyright and Related Rights.
The medicinal leech has powerful, well-developed muscles. Muscles lie under an outer layer of integumentary tissue, the cells of which reliably protect them from harmful environmental influences. The muscles, which make up 70% of the leech's total body volume, are heterogeneous in structure. It is represented by several layers of specialized muscle bundles.
Just under the skin are the circular muscles. Their contraction in response to nerve impulses causes an increase in the length of the leech’s body: it elongates. Under the ring layer there are bundles of longitudinal muscles, which are best developed in the leech. The activity of these muscles causes a decrease in the length of the leech's body, causing it to shrink. The medicinal leech also has developed dorso-abdominal muscles.
The digestive organs of the medicinal leech are of greatest interest to medicine and zoology, since it is the features of this physiological system that make it possible to use the leech as a remedy. The leech is defined by scientists as a true hematophage (from the Greek haima - blood and phagos - devouring).
This definition is absolutely correct, since the medicinal leech does not feed on anything other than blood. At the same time, it is capable of assimilating exclusively the blood of vertebrate animals. differs from other hirudins, which have adapted to eating all kinds of aquatic and terrestrial invertebrates. The medicinal leech is adapted to consuming the blood of any vertebrates, but its main host can only be large mammal, including people.
The digestive tract of the leech opens at the anterior end of the body with the mouth opening. In the depths of the oral cavity, immediately in front of the pharynx, there are three small white bodies in the shape of a half lens. This is the jaw apparatus of a leech. Two jaws are lateral, and the third is dorsal. Each jaw bears from 80 to 90 small teeth. The teeth of a medicinal leech are very sharp, which allows it to quickly bite through the thick skin of warm-blooded animals.
The leech's pharynx is short, it is surrounded by thick bundles of powerful muscles. This muscle compresses the pharyngeal walls and promotes active swallowing of blood from the wound cut by the denticles. Following the pharynx is the esophagus, which passes into the multi-chamber stomach, also called the gastric intestine. An intensive process of blood accumulation occurs here, which is served by 10 pairs of segments capable of expanding.
The gastric intestine is the most voluminous part of the digestive system of a medicinal leech. Segments of the stomach, called chambers, are formed by narrowing in several places of the originally straight tube of the alimentary canal. The constrictions divided the tube into a number of partially separate sections, the walls of each of them subsequently began to protrude. Lateral protrusions of the chambers led to the appearance of pouch-like processes, increasing the volume of segments of the gastric intestine.
Throughout this part of the digestive canal, the size of the sections is different, because bag-like protrusions are developed unequally. The largest segments are located at the end of the stomach; closer to the pharynx they become smaller. This structure of the stomach intestine, together with its ability to stretch, gives the leech the ability to suck out (take away, as they also say) the blood of the owner.
The stomach reserves provide a well-fed leech for several months. At the same time, if we take into account the total volume of blood circulating in the mammal’s body, the leech does not take so much from the owner. A medium-sized leech, reaching a mass of 2 g, sucks no more than 8 ml of blood, although in principle it is capable of absorbing up to 10-15 ml, i.e. almost 8 times its own weight. The stomach segments of a healthy leech serve as a reliable storage of blood, which does not clot in them, does not become infected with microbes, and does not deteriorate for any other reason.
Previously, doctors forced leeches to regurgitate sucked blood in order to empty their stomachs and force them to suck blood again. This made it possible to reuse leeches. Belching occurs when a leech is immersed in vinegar, wine or saline solution. Artificial belching is also caused by squeezing the leech with your fingers. Now such techniques are not used; doctors do not force leeches to regurgitate, since repeated regurgitation medicinal qualities leeches are significantly reduced, their delicate digestive system is injured. Under natural conditions, healthy leeches never regurgitate.
Digestive system of a medicinal leech: 1 - jaws and pharynx; 2 - gastric intestine; 3 - terminal gut; 4 - anus
If blood accumulation occurs in the leech’s stomach, then the digestion process takes place in the terminal intestine. It is very short, less than 1/4 of the length of the leech’s body and resembles a thin straight tube. Blood enters this tube in small portions for digestion. The shortest section of the digestive canal is the anus. Digested blood residues enter here, forming feces, which are then evacuated through the anus (powder).
Leeches have bowel movements regularly, up to several times a day. Therefore, the water in the vessel where used leeches are stored periodically becomes colored. Frequent coloring of water should not cause any concern, since it only indicates the health of the leeches and the normality of their physiological functions. Clogging of water that occurs from time to time does not cause any harm to leeches if the water is regularly changed.
Caring for leeches is necessary. It consists not only in periodically refreshing the water in the vessel. When keeping leeches, maintaining normal light and temperature conditions is important. However, it is strictly forbidden to feed leeches. Only hungry leeches, capable of greedily sucking blood, are suitable for medicinal use.
In addition to sharp teeth and a powerful throat, the salivary glands of the leech are the most important device for sucking blood. As a matter of fact, it is the function of these glands that determines the interest of doctors in the leech. Salivary glands leeches are located around the pharynx, forming a large accumulation of negligible whitish balls.
Each such ball is a gland body consisting of a single cell. Inside this cell there is a large nucleus, which has a small nucleolus with chromosomes and filled with chromatin grains. The rest of the internal space of the cell is filled with a special liquid - cytoplasm, in which grains producing the secretion of the salivary glands are suspended. This secretion, i.e. the final product of biochemical synthesis, flows through the excretory duct and mixes with the water present in the leech’s body. As a result, saliva containing biologically active substances is formed.
Each glandular cell is supplied with a duct, thus connecting to the jaws. The ducts gradually, as they approach the jaws, unite into bundles. These tufts run inside the jaws, ending on their surfaces and opening into small openings between the teeth. From these holes saliva enters the wound bitten by the leech.
The secretion of saliva, as shown by the experiments of L. Shapovalenko, occurs continuously during the entire act of sucking. The active components of the secretion of the salivary glands determine its biological and pharmacological properties.
Biochemical reactions that require high temperatures or strong acids and alkalis cannot take place in living cells. To cause transformations of various substances, human body has a reserve of some specific compounds called enzymes. They are active at normal body temperature and act as regulators of intra- and extracellular transformations of organic substances.
Since the digestion process begins already during chewing, during the processing of food with saliva, it is here that enzymes first react, breaking down and converting the nutrients contained in food. We see the same thing in leeches. The main enzyme of the salivary glands of the leech is hirudin, but some other enzymes also play an important role: hyaluronidase, destabilase, orgelase, antistasin, decorzin, viburnum, eglin. In total, leech saliva contains up to 20 active proteins.
Previously, we spoke mainly about enzymes that accelerate chemical transformations. These are catalysts, i.e. reaction activators. However, there are also regulators of reverse action, also contained in the secretion of the salivary glands of the leech. They are inhibitors, i.e. they suppress the activity of other enzymes and dampen certain reactions.
Hirudin and many other substances in the secretion of the salivary glands of the medicinal leech are both inhibitors that suppress the blood coagulation reaction and catalysts that break down many proteins in our plasma. Chemical analysis of the tissues of the medicinal leech revealed a reduced content of hirudin in all parts of its digestive system.
In the terminal gut, hirudin is broken down by another type of enzyme. Thanks to this, blood clotting is possible here, the clots of which are immediately broken down by digestive juices into amino acids. This is how the blood mass is digested in the leech’s intestines.
The medicinal leech has a nervous system built according to a completely special model, different from the nervous organization of lower or, on the contrary, higher representatives of the animal kingdom. More primitive jellyfish and hydra have a dense network of neurons instead of a nervous system ( nerve cells), controlling the reactions of these creatures.
Of the special sensory organs, the leech has only eyes, although they are represented in large numbers. Remember that a leech has 10 eyes. They are spherical chambers that do not have a lens and carry 50 photoreceptors. Judging by the structure of the eyes, the leech does not perceive a complete image. But she responds well to many external influences, although she lacks the organs of smell and touch. Irritations are captured by sensitive skin cells, which are either elements of sensory kidneys (receptors) or nerve endings. Most of the sensory buds and nerves are concentrated at the anterior end of the leech’s body.
Nerve fibers extend from the kidneys and other nerve cells of the skin, gathering as they unite into nodes of the nerve chain. Almost every segment of the leech on the ventral side has such a node. The nodes are interconnected, ensuring the reception and transmission of impulses in the nervous system.
Taken together, this entire formation is called the abdominal nerve chain, which performs the same functions in a leech as the central one. nervous system(head and spinal cord) in humans. The largest nodes of the chain are the suprapharyngeal and subpharyngeal nodes located at the head end of the body. The suprapharyngeal node is the largest. It is connected to the subpharyngeal by special bridges, so that a ring is formed around the leech’s pharynx, which zoologists call the peripharyngeal nerve ganglion.
It is similar in importance to the human brain, although, of course, it is not equivalent to it and differs in structure. The “brain” of a leech is relatively simple. Its two components (suprapharyngeal and subpharyngeal nodes) complement each other, since the action of one compensates and partially neutralizes the action of the other.
Despite the seeming primitiveness of the sensory perception of leeches, they are excellent at orienting themselves in space. Their sense of smell, taste and touch, in the absence of corresponding sensory organs, are unusually developed, which contributes to their success in searching for prey. First of all, leeches respond well to odors emanating from objects immersed in water. Irritating odors force the leech to hastily move to another place. Leeches cannot tolerate foul-smelling water.
Of the many different odors - pleasant and unpleasant - animals highly accurately recognize those emanating from people and large mammals, i.e., potential hosts. This is proven by simple but cleverly designed experiments that can be easily repeated at home. For example, 2 clean plugs are lowered into water. In this case, one of them must be lowered with a gloved hand, the other with a “bare” hand. As a result, most leeches invariably stick to the plug that has been in contact with the human skin rather than the glove. Leeches will become much more active if the smell of a person on the plug is increased (for example, by holding it under your armpit for a while).
Of course, the smell of blood is most attractive to leeches. Their reaction to this stimulus is immediate. It is worth adding a few drops of the blood of a mammal to a vessel with leeches, and the leeches, if they are hungry and healthy, quickly take a hunting “stance.” They rise at the rear ends of the body, stretching out, and begin to sway vigorously. The front end of the body produces movements that demonstrate the leeches' attempts to attach themselves to a potential victim.
Among other things, it is necessary to mention that leeches have the so-called. thermal feeling. Thermoreceptors are present in a great variety of living creatures, but only in some highly organized bloodsuckers are they specialized. Temperature-sensitive receptors in human skin are adapted to distinguish the degree of heating of the surfaces of different objects over a wide temperature range. Our skin, therefore, can only signal the danger of thermal damage to the skin - due to burns or frostbite.
Leeches, like South American vampires (bats), detect slight differences in the heating of surfaces. This makes some biological sense, since some worms have evolved to develop thermotropism (a tendency to move to areas with temperatures slightly higher than normal).
When attached to the skin, the leech does not immediately begin to bite. She persistently searches around for the warmest patch of skin. The same instinct that drives the blood-sucking bats of the New World tells the medicinal leech that the warmest areas of the skin are richest in blood. The capillaries here are overcrowded, intense microcirculation in the tissues contributes to their greater warming and increases the power of the flow of infrared (thermal) radiation.
If for a vampire an error in determining the temperature of parts of the victim’s body is completely indifferent, then for a leech it is undesirable to make mistakes. After all, in all warm-blooded creatures, when they get into cool water, the capillaries narrow, as a result of which blood microcirculation becomes slower. That is why the amount of blood taken by a leech strictly depends on the point of the skin where it sticks. To take away more blood, the leech must find an area with increased microcirculation, where the capillaries are slightly narrowed.
The reactions of leeches to odors, water fluctuations and the temperature of human skin have been thoroughly studied by zoologists over the past two centuries, and even earlier people managed to superficially explore the sense of smell, touch and other senses of a leech, based on personal observations. The conclusions obtained in this case form the basis of leech-catching, leech breeding and bdeltechnics, and in particular the technique of placing medicinal leeches on patients.
At the same time, for the practical needs of leech breeding, studies of the leech’s reproductive system and the characteristics of its reproduction are no less important. As mentioned in the previous section, leeches are hermaphrodites, that is, they have a dual reproductive system, including both male and female genitalia.
Only leeches of 3 years of age reach sexual maturity, since they have already gained the necessary mass for the body to produce reproductive products - eggs and sperm. Leech, reproducing once a year, summer time, during its life brings from 3 to 4 offspring.
Laboratory studies have shown that the average life expectancy of a leech is 6 years. Scientists do not know for certain how long wild individuals live, although it is possible that leeches have their own long-livers.
Loading...